PSI - Issue 56

Kevin Moj et al. / Procedia Structural Integrity 56 (2024) 120–130 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Keywords: Selective Laser Melting. Computer Tomography. Finite Element Method. Numerical Homogenization;

1. Introduction Metal additive manufacturing is the process of creating three-dimensional objects from metal by applying successive layers of material. It enables the production of complex geometries and structures that would be difficult or impossible to achieve using traditional manufacturing methods. Among other applications. the technology is widely used in the aerospace. medical and automotive industries. During recent years. additive manufacturing has become a promising technique for creating cellular structures with customized geometries and properties. Using 3D printing technology. complex internal architectures can be created that cannot be achieved by traditional manufacturing methods. Such cellular structures have potential applications in various fields. such as biomedical engineering. aerospace and energy storage (Al-Ketan, Rowshan, and Abu Al-Rub 2018; Maconachie et al. 2019; Zadpoor 2019). However. there is still no clear consensus on the minimum number of cells at which the structure exhibits a constant effective Young's modulus. This is especially important for experimental studies. The optimal number of cells depends on the specific application and the material used. Other key parameters are the relative density. i.e. the degree of filling with the material. and the topology of the unit cell (Cantaboni et al. 2022; Mehboob et al. 2018; Mines 2019; Yan et al. 2021). Cellular structures can be simulated using three basic methods: solid-based analysis. homogenization and beam based analysis. In solid-based analysis. a cellular structure is modeled as a solid object. and its mechanical behavior is analyzed using finite element analysis. Such an approach allows a detailed understanding of the mechanical properties of a lattice structure. including its deformation. stresses and strains. However. it can be computationally expensive and time-consuming. especially for complex structures. Beam-based analysis is a simplified method for analyzing cellular structures that treats the structure as a collection of interconnected beams. This simplifies the geometry of the structure and reduces computational time significantly. Numerical homogenization is a method of analyzing the effective mechanical behavior of cellular structures by considering them as homogeneous materials. This method simplifies the complexity of the lattice structure and allows for faster simulations and simpler analysis. The homogenization technique involves determining the mechanical properties of a lattice structure using an effective material model. This model captures the overall mechanical behavior of the structure. including its stiffness and strength. However. the accuracy of numerical homogenization can be improved by using a model obtained by CT scanning (Cantaboni et al. 2022; Chatzigeorgiou et al. 2022; Doroszko, Falkowska, and Seweryn 2021; Jiang et al. 2021; Mehboob et al. 2018; Yan et al. 2021) . The purpose of this study was to determine an algorithm that would allow the determination of the minimum number of individual cells at which the cell structure exhibits a constant effective Young's modulus. In addition. a homogenization method was optimized for cell structures (Al-Ketan et al. 2020) . 2. Methods 2.1. Design and production of the cellular structures Cellular structures were designed using nTopology software. which is specifically tailored to create advanced geometries. The implicit modeling method allows the generation of more complex shapes. and the available design methodology makes it possible to control different variants of the design using formulas. tests. simulations and other data. The detailed design process is presented in (Moj et al. 2022). In Figure 1. the tested specimens are presented. It was determined to print samples with a variety of single cell topologies. changing both the size of a single cell and the